As of version 7.20, the WWT WebGL engine supports a “freestanding mode” that
allows it to run in a purely self-contained fashion — it will not make any
requests to the
worldwidetelescope.org servers for supporting data. This
disables a number of the engine’s capabilities, but may be of interest for WWT
adopters who are unwilling or unable to depend on external services.
Limitations of Freestanding Mode🔗
Activating the freestanding mode causes the engine to be limited in the following ways:
- No default sky map. WWT’s built-in DSS sky map will not be available. The sky view will only be able to show an empty, black sky unless you import your own all-sky survey(s).
- No built-in image sets. Likewise, WWT’s built-in database of all-sky maps and “study” images will not be available. If you wish to show any surveys or studies, you must load them in yourself.
- No 3D “solar system” mode. The engine won't prevent you from activating
this mode, but it will be virtually useless. Many aspects of this mode rely on
WWT APIs, including:
- COSMOS galaxies database
- Hipparcos star database
- Minor planets database
- Planet and moon textures
- Most tours will not work. If a tour relies on assets provided by the core WWT APIs, they will not have been loaded and will be missing. If you construct a tour that does not rely on these assets, it will work as expected.
- No automatic proxying. When fetching web resources, if the WWT engine runs
into a problem that seems to be due to HTTP/HTTPS mismatches or CORS
restrictions, it will reroute the relevant requests through a proxy service on
worldwidetelescope.orgthat works around the issue(s). In freestanding mode, this behavior is disabled.
- No constellation artwork. These images are pulled from a WWT web API.
- No ISS (International Space Station) coordinate frame or 3D model. WWT’s support for showing the ISS depends on web APIs to provide its current orbital parameters and a 3D model, so this support must be disabled in freestanding mode.
- Tour URLs in WTML folders must be specified. In the standard mode, references to tours can be resolved to a URL that fetches their data based on a UUID registered with the WWT webservice. This is not possible in freestanding mode.
- No automatic ID-based thumbnail images for tours. As above. These will use a generic star thumbnail image instead.
- No automatic name-based thumbnail images for Places in WTML folders. These will use a generic star thumbnail image instead.
- No automatic Bing-based DEM data for Mercator projection imagesets. Some Earth data have elevation data automatically attached. This feature will be deactivated.
Activating Freestanding Mode🔗
<template> <div> <WorldWideTelescope id="wwt" wwt-freestanding-asset-baseurl="https://myassets.org/wwtengine" ></WorldWideTelescope> <div id="my-ui-controls">...</div> </div> </template>
This value is a base URL that will be used to look up simple, static data assets
used by the engine. The default value used in the production version of WWT is
https://web.wwtassets.org/engine/assets, and you can use that value here if
you don’t mind depending on
If you're using the bundled TypeScript model, you can activate the mode with an analogous parameter, InitControlSettings#freestandingAssetBaseurl, when calling the WWTInstance constructor provided in the @wwtelescope/engine-helpers package.
Currently, the engine assets are not indexed elsewhere. To serve up your own assets, download the following files from the default baseurl given above:
The following assets are only used in 3D mode and so are unlikely to be needed if you are using WWT in freestanding mode:
galimg/gal_$N.jpgfor N ranging from